Example problem showing how to find the rate constant k from the half-life of a first order reaction.

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Chemistry on Khan Academy: Did you know that everything is made out of chemicals? Chemistry is the study of matter: its composition, properties, and reactivity. This material roughly covers a first-year high school or college course, and a good understanding of algebra is helpful.

1. Introduction to chemistry
2. Elements and atoms | Atoms, compounds, and ions | Chemistry | Khan Academy
3. Introduction to the atom | Chemistry of life | Biology | Khan Academy
4. Orbitals | Electronic structure of atoms | Chemistry | Khan Academy
5. More on orbitals and electron configuration | Chemistry | Khan Academy
6. Electron Configurations
7. Electron configurations 2 | Electronic structure of atoms | Chemistry | Khan Academy
8. Noble gas configuration (old, low volume)
9. Noble gas configuration | Electronic structure of atoms | Chemistry | Khan Academy
10. Valence Electrons
11. Groups of the Periodic Table
12. Periodic Table Trends: Ionization Energy
13. Other Periodic Table Trends
14. Ionic, covalent, and metallic bonds | Chemical bonds | Chemistry | Khan Academy
15. Molecular and Empirical Formulas
16. The mole and Avogadro's number | Atoms, compounds, and ions | Chemistry | Khan Academy
17. Formula from Mass Composition
18. Another mass composition problem | Chemistry | Khan Academy
19. Balancing Chemical Equations
20. Stoichiometry | Chemical reactions and stoichiometry | Chemistry | Khan Academy
21. Stoichiometry: Limiting reagent | Chemical reactions and stoichiometry | Chemistry | Khan Academy
22. Ideal gas equation: PV = nRT | Chemistry | Khan Academy
23. Ideal gas equation example 1 | Chemistry | Khan Academy
24. Ideal gas equation example 2 | Chemistry | Khan Academy
25. Ideal gas equation example 3 | Chemistry | Khan Academy
26. Ideal gas equation example 4 | Chemistry | Khan Academy
27. Introduction to partial pressure | Gases and kinetic molecular theory | Chemistry | Khan Academy
28. Partial pressure example | Chemistry | Khan Academy
29. States of matter | States of matter and intermolecular forces | Chemistry | Khan Academy
30. States of matter follow-up | States of matter and intermolecular forces | Chemistry | Khan Academy
31. Specific heat, heat of fusion and vaporization example | Chemistry | Khan Academy
32. Chilling water problem | States of matter and intermolecular forces | Chemistry | Khan Academy
33. Phase diagrams | States of matter and intermolecular forces | Chemistry | Khan Academy
34. Van der Waals forces | States of matter and intermolecular forces | Chemistry | Khan Academy
35. Covalent networks, metallic crystals, and ionic crystals | Chemistry | Khan Academy
36. Vapor pressure | States of matter and intermolecular forces | Chemistry | Khan Academy
37. Suspensions, colloids and solutions | Chemistry | Khan Academy
38. Solubility and intermolecular forces | Chemistry | Khan Academy
39. Boiling point elevation and freezing point depression | Chemistry | Khan Academy
40. Introduction to kinetics | Energy and enzymes | Biology | Khan Academy
41. Reactions in equilibrium | Chemical equilibrium | Chemistry | Khan Academy
42. Group trend for ionization energy | Periodic table | Chemistry | Khan Academy
43. Keq intuition | Chemical equilibrium | Chemistry | Khan Academy
44. Keq derivation intuition | Chemical equilibrium | Chemistry | Khan Academy
45. Heterogeneous equilibrium | Chemical equilibrium | Chemistry | Khan Academy
46. Le Chatelier's principle | Chemical equilibrium | Chemistry | Khan Academy
47. Introduction to pH, pOH, and pKw
48. Acid Base Introduction
49. pH, pOH of strong acids and bases | Chemistry | Khan Academy
50. pH of a Weak Acid
51. pH of a Weak Base
52. Conjugate acids and bases
53. pKa and pKb relationship | Acids and bases | Chemistry | Khan Academy
54. Buffers and Henderson-Hasselbalch | Chemistry | Khan Academy
55. Strong Acid Titration
56. Buffer capacity | Buffers, titrations, and solubility equilibria | Chemistry | Khan Academy
57. Weak Acid Titration
58. Private video
59. Titration roundup | Buffers, titrations, and solubility equilibria | Chemistry | Khan Academy
60. Introduction to Oxidation States
61. More on Oxidation States
62. Hydrogen Peroxide Correction
63. Redox Reactions
64. Galvanic Cells
65. Types of decay | Nuclear chemistry | Chemistry | Khan Academy
66. Half-life and carbon dating | Nuclear chemistry | Chemistry | Khan Academy
67. Exponential decay formula proof (can skip, involves calculus) | Chemistry | Khan Academy
68. Introduction to exponential decay | Nuclear chemistry | Chemistry | Khan Academy
69. More exponential decay examples | Nuclear chemistry | Chemistry | Khan Academy
70. Macrostates and microstates | Thermodynamics | Physics | Khan Academy
71. Quasistatic and reversible processes | Thermodynamics | Physics | Khan Academy
72. First law of thermodynamics / internal energy | Thermodynamics | Physics | Khan Academy
73. More on internal energy | Thermodynamics | Physics | Khan Academy
74. Work from expansion | Thermodynamics | Physics | Khan Academy
75. PV-diagrams and expansion work | Thermodynamics | Physics | Khan Academy
76. Proof: U = (3/2)PV or U = (3/2)nRT | Thermodynamics | Physics | Khan Academy
77. Work done by isothermic process | Thermodynamics | Physics | Khan Academy
78. Carnot cycle and Carnot engine | Thermodynamics | Physics | Khan Academy
79. Proof: Volume ratios in a carnot cycle | Thermodynamics | Physics | Khan Academy
80. Proof: S (or entropy) is a valid state variable | Thermodynamics | Physics | Khan Academy
81. Thermodynamic entropy definition clarification | Physics | Khan Academy
82. Reconciling thermodynamic and state definitions of entropy | Physics | Khan Academy
83. Entropy intuition | Thermodynamics | Physics | Khan Academy
84. Maxwell's demon | Thermodynamics | Physics | Khan Academy
85. More on entropy | Thermodynamics | Physics | Khan Academy
86. Efficiency of a Carnot engine | Thermodynamics | Physics | Khan Academy
87. Carnot efficiency 2: Reversing the cycle | Thermodynamics | Physics | Khan Academy
88. Carnot efficiency 3: Proving that it is the most efficient | Physics | Khan Academy
89. Enthalpy | Thermodynamics | Chemistry | Khan Academy
90. Heat of formation | Thermodynamics | Chemistry | Khan Academy
91. Hess's law and reaction enthalpy change | Chemistry | Khan Academy
92. Gibbs free energy and spontaneity | Chemistry | Khan Academy
93. Gibbs free energy example | Thermodynamics | Chemistry | Khan Academy
94. More rigorous Gibbs free energy / spontaneity relationship | Chemistry | Khan Academy
95. A look at a seductive but wrong Gibbs/spontaneity proof | Chemistry | Khan Academy
96. Stoichiometry example problem 1 | Chemistry | Khan Academy
97. Stoichiometry example problem 2 | Chemistry | Khan Academy
98. Limiting reactant example problem 1 | Chemistry | Khan Academy
99. Empirical and Molecular Formulas from Stoichiometry
100. Example of Finding Reactant Empirical Formula
101. Stoichiometry of a Reaction in Solution
102. Another Stoichiometry Example in a Solution
103. Molecular and Empirical Forumlas from Percent Composition
104. Acid base titration example | Chemistry | Khan Academy
105. Spectrophotometry introduction | Kinetics | Chemistry | Khan Academy
106. Spectrophotometry example | Kinetics | Chemistry | Khan Academy
107. Hess's law example | Thermodynamics | Chemistry | Khan Academy
108. Vapor pressure example | Chemistry | Khan Academy
109. Change of state example | States of matter and intermolecular forces | Chemistry | Khan Academy
110. Small x approximation for small Kc | Chemistry | Khan Academy
111. Small x approximation for large Kc | Chemical equilibrium | Chemistry | Khan Academy
112. pH and pKa relationship for buffers | Chemistry | Khan Academy
113. 2015 AP chemistry free response 5a
114. AP Chemistry multiple choice sample: Boiling points
115. Rate constant k from half-life example | Knetics | Chemistry | Khan Academy
116. Ways to get a buffer solution | Chemistry | Khan Academy
117. Comparing Q vs K example | Chemical equilibrium | Chemistry | Khan Academy
118. Finding units of rate constant k | Knetics | Chemistry | Khan Academy
119. Calculating internal energy and work example | Chemistry | Khan Academy
120. Ionic bonds and Coulombs law
121. Bond enthalpy and enthalpy of reaction | Chemistry | Khan Academy
122. Introduction to reaction quotient Qc | Chemical equilibrium | Chemistry | Khan Academy
123. Le Chatelier's principle: Worked example | Chemical equilibrium | Chemistry | Khan Academy
124. Conjugate acid-base pairs | Acids and bases | Chemistry | Khan Academy

An introductory college-level chemistry course that explores topics such as atoms, compounds, and ions; chemical reactions and stoichiometry; ideal gases; chemical equilibrium; acids and bases; kinetics; thermodynamics; redox reactions and electrochemistry; and a whole lot more!